1. Field of the Invention
This invention concerns a catalytic process for making tetra(methyl-ethyl) lead redistribution compounds which are useful as fuel antiknocks.
2. Description of the Prior Art
Heretofore, tetra(methyl-ethyl)lead redistribution compounds have been prepared according to processes characterized in that tetramethyl lead was a necessary reactant, either added as such or formed in situ. Representative of such prior art redistribution processes utilizing tetramethyl lead as a reactant are the following: contacting an alkali metal trialkyl plumbide with an alkylating agent in an aprotic medium according to U.S. Pat. No. 3,539,608; contacting sodium lead alloy, methyl chloride and tetraethyl lead in the presence of a catalyst according to U.S. Pat. No. 3,478,072; contacting at least two mixed alkyl lead compounds with a boron trifluoride alkyl etherate according to U.S. Pat. Nos. 3,151,141 and 3,151,142; contacting at least two mixed alkyl lead compounds with a silica-magnesia catalyst according to U.S. Pat. No. 3,527,780; and contacting alkyl lead compounds with organometallic halides or metal halides according to Calingaert et al. in J. Am. Chem. Soc. 61, 2748 ffg. and 3300 ffg. (1939).
A reaction known in the literature but one which does not produce redistribution products is disclosed by Korshunov et al. in J. Gen. Chem. (USSR) 39, 3100 (1959). In the disclosed reaction, tetraethyl lead is contacted with radioactive ethyl bromide in the presence of a catalyst such as FeCl.sub.3, AlBr.sub.3, AlEt.sub.3 and AlCl.sub.3. The reference process merely replaces some ethyl groups of the tetraethyl lead starting reactant with radioactive (thus traceable) ethyl groups from the ethyl bromide.